It's a fascinating powder.
Nikt is the Swedish name for the spores of Lycopodium - we have two common species, Lycopodium clavatum and Lycopodium annotinum, but I expect that the unripe seedheads of any Lycopodium can be gathered and dried (in a paper bag!) for their spores. (Unless they're rare or endangered, of course.)
And the old books say that if you throw a handful of nikt onto a fire, it'll whoosh into a very strong flame. I tried to get it to burn with a couple matches, but that didn't work at all - possibly the temperature needs to be way higher.
Pic: Dried sporeheads, nikt and a drop of water. What works, though, is the water-repellant part of nikt. It's wonderful: pour a few drops of water onto nikt, and those drops, covered in nikt, will roll all around the plate you're trying it on. Pour a bit more water, and the nikt-water-bubbles will burst. However, if you then pour the nikt'n'water off that plate, you'll have water drops covered in nikt rolling all over the place again.
Nikt was used to coat pills, so they would repel moisture. It was also used as a diaper powder. I'm sure that it'd still be widely used, were it not for the unfortunate fact that between 10 and 20 % of kids are (or get) allergic to nikt.
Lovely stuff, is nikt. Pick some unripe green (or ripening yellowish) seedheads if you ever have the chance, and play around with the powder you get as the seedheads dry out.